This week’s “This Is Us” featured plenty of emotional moments, but it saved perhaps the biggest one for the very end.

The NBC drama’s latest episode focused on Kevin (Justin Hartley) continuing to struggle with addiction after returning to his high school for an awards ceremony. Flashback scenes offered memories from his football-hero teen years.

After Kevin loses a necklace belonging to late father Jack (Milo Ventimiglia), the “Manny” star breaks down at the end of the episode and visits Randall (Sterling K. Brown). Kevin tells his brother he has something to say and appears to be about to come clean about his addictions, but Randall instead assumes that Kevin is referring to another topic.

As to be expected, the stunning revelation led to a litany of surprised reactions on social media as fans tried to process the fact that Kate (Chrissy Metz) and beau Toby (Chris Sullivan) appear to have suffered a miscarriage.

“On one hand, wish we’d gotten to know Toby and Kate’s baby, but on the other hand, I’m so confident that #ThisIsUs is going to cover this common and devastating issue with dignity and it needs to be covered,” one fan tweeted.

“When will Kate get her happy ending!!!???” another devotee wrote. “Toby and Kate [were] so happy to be having a baby … just whyyyyy did this have to happen!!!!!”

On one hand wish we'd gotten to know Toby and Kate's baby, but on the other hand, I'm so confident that #ThisIsUs is going to cover this common and devastating issue with dignity and it needs to be covered. @NBCThisisUs@ChrissyMetz@SullivanTweet always do a great job

'This Is Us': 7 Craziest Fan Theories on How Jack Dies (Photos)

How does Jack Pearson die? The internet has some theories on Milo Ventimiglia's much-discussed patriarch on NBC's popular series, "This Is Us." His end has been described by cast members as "unexpected" and "extremely heartbreaking." Now fans have put their sleuthing hats on to solve the mystery before the answer is revealed. Here is some of the zanier speculation.

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SuicideIt's hard to imagine Papa Pearson willingly leaving the family he clearly adores, but eagle-eyed fans point to Randall's words when he was trying to stop a co-worker from committing suicide at the company Christmas party: You need to be there for your kids.

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Plane crashThis would seem to come out of nowhere for casual viewers, but die-hard fans have picked up on several references to planes on the show. Why is Kate so scared of flying? Why did Kevin destroy his toy airplanes?

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Heart attackJack's unhealthy habits -- in addition to the drinking -- have been picked up by some fans, who believe cardiac arrest will be the cause of death, compounded by Kate's emotional response to Toby's heart issues. But honestly, this just sounds way too normal for a show that's all about throwing curveballs.

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Jack's father kills himThis is definitely a stretch, but we know Jack borrowed money from his abusive father without revealing anything about his life or his family. Could the elder Pearson show up decades later in a rage? Uh, probably not, but that's one theory.

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Car accidentThis is the theory the show sets up as viewers watched Jack drive off to Cleveland to Rebecca as Kate's voice-over tells us she blames herself for her dad's death. That's what makes it pretty unlikely that Jack gets taken out before he's reunited with his wife. Wouldn't you agree?

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Long downfall set off by injuryOkay, he probably doesn't die in a car accident in the Season 1 finale, but he could get injured -- seriously injured. So injured that he begins a downward spiral that further strains his marriage and ultimately leads to his death. And it all began when Kate convinced him to drive to Cleveland. It's not too far-fetched, plus it would keep Ventigmilia alive and kicking in flashbacks for a good while longer.

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Jack's not really deadThis is a doozy and probably the most unlikely, but what if Jack isn't actually dead? This insane theory involves a car thief who knocks him unconscious, causing amnesia, and his oblivious father, who never knew he had a family to alert to his real whereabouts. So, Kate's been holding onto some stranger's ashes this entire time? Yikes.

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Plane crash? Suicide? Is Milo Ventimiglia’s character secretly alive?

How does Jack Pearson die? The internet has some theories on Milo Ventimiglia's much-discussed patriarch on NBC's popular series, "This Is Us." His end has been described by cast members as "unexpected" and "extremely heartbreaking." Now fans have put their sleuthing hats on to solve the mystery before the answer is revealed. Here is some of the zanier speculation.